Electron Documentation

Electron has APIs to configure the app's icon in the macOS Dock. A macOS-only
API exists to create a custom dock menu, but
Electron also uses the app's dock icon to implement cross-platform features
like recent documents and
application progress.

The custom dock is commonly used to add shortcuts to tasks the user wouldn't
want to open the whole app window for.

Dock menu of Terminal.app:

To set your custom dock menu, you can use the app.dock.setMenu API, which is
only available on macOS: